This invention relates generally to protective headgear, and more particularly, to headgear designed to facilitate reducing skull and brain injuries.
Modern headgear, including helmets, is often worn by individuals during physical activities, including sporting events and exercise, to help protect the wearer from head injuries. At least some known head protective devices are manufactured to satisfy safety and/or legal regulations set by various federal and state agencies, and/or organizations governing specific activities. For example, military helmets may be manufactured to withstand different requirements than those required by professional sports organizations, such as Major League Baseball (MLB) or the National Football League (NFL). Generally, the efficacy of all protective headgear is constantly examined to facilitate enhanced head protection for the wearer. Moreover, because brain damage is cumulative and is permanent, no corrective measure can undo damage resulting from a brain injury and as such, the focus of preventing such injuries from occurring has been elevated.
Generally, protective headgear is designed to satisfy specific requirements relating to inter alia the maximum acceleration that may occur in the center of the wearer's brain at a specified load, and/or to withstand the maximum impact that the wearer's head may be exposed to during a specific activity. Typically, during testing of at least some known protective headgear, a dummy skull equipped with a protective headgear, such as a helmet, is subjected to a radial impact. More specifically, if the wearer's head is not in motion when impacted by an object, generally the impact creates a linear acceleration and a point load (i.e., a force concentrated over a small area). Such an impact may result in a skull fracture and/or mild traumatic brain injury (MTBI). More specifically, the severity of injury to the wearer may vary depending on several factors, including the magnitude and direction of the impact. When an external impact shakes the brain inside the skull, the shaking may result in temporarily disrupting the brain from working normally by disturbing or damaging electrical, chemical, and/or anatomical function connections within the brain, which may result in MTBI.
At least some known protective headgear attempt to absorb as much of the energy transmitted by radial impact with another object, including equipment worn or used by another person, a body part of another person, the ground, and/or a structural object, and/or attempt to deflect impacts occurring at an oblique angle to the helmet. Moreover, at least some known protective headgear is designed to reduce brain concussions to the wearer. To reduce the effect of an external impact to the wearer, at least some known helmets include at least a hard outer shell, often fabricated from a plastic or a composite material, and an energy absorbing layer called a liner. Some known helmets also include an internal head-fitting structure such as a suspension webbing, a foam layer, fluid-filled bladders, and/or a padding molded to fit a specific wearer. The hard exterior plastic shells of known helmets and the interior form-fitting structures have the ability to absorb a certain amount of the impact energy induced to the wearer when the helmet is impacted by an object. Any impact energy not absorbed by the helmet is transferred to the skull of the wearer, which may result in injuries ranging from mild concussions or mild traumatic brain injury (MTBI) to severe brain damage. Helmets fabricated as such, provide some impact-absorption capacity to the wearer for impacts that are primarily radially-directed, but typically such helmets generally provide far less energy absorption for impacts induced non-radially to the helmet.
Other known helmets may include impact-absorbing compression members that compress when subjected to an impact. For example, at least some of such helmets include cells that are compressible when the helmet is pressed against the wearer's head when subjected to impact forces. At least some of the known compression cells may be filled with a resilient material, such as foam. However, depending on the size and density of the resilient material, such cells may be prone to bottoming out when compressed between the helmet and the wearer's head. Once bottomed out, the energy absorption ability of such cells is limited at best. Simply increasing the density of the compressible material and/or increasing the thickness of the cells may provide only limited benefits and may require significant increases in the overall size of the helmet. Other known compression cells are fabricated from materials that are more resilient than foam and that return to their original shape after being compressed. Generally such compression cells are hollow and expel air as they are compressed between the helmet and the wearer's head. As such, depending on the size and placement of the cells in the area of an impact to the helmet, only one or a limited amount of cells may be compressed, such that a point load, of lesser magnitude than the original impact, may still be induced to the wearer over a relatively small concentrated area. As such, the energy-absorption capabilities and benefits of known helmets including such compression cells may be limited.